1. Introduction

An investigation was done on the average amount of Vitamin C found in oranges. It has been shown that the average amount was 70mg in an average-sized orange.

Research was also done to find a more reliable way to measure the amount of Vitamin C in oranges.

Laila M. Nikaien did a research about the rate of loss of vitamin C in the fruit itself and in the juice. She found out that oranges that are placed in a place with a higher temperature lost vitamin Cs at a faster rate. However, the rate of loss of vitamin C in orange juice was slower.

Nicholas J. Hickernell has done a research about the same question. He picked three oranges on three different days, 19 December 2003, 6 January and 12 January. He made a Vitamin C solution, an iodine solution and a starch solution to test how much Vitamin C is in oranges the longer they stay in the tree. He squeezed the juice from each orange and tested it by using a titration method. The results showed that the orange picked on December 19 took six drops to titrate. The orange picked on 6 January took seven drops to titrate it. The orange picked on 12 January took ten drops to titrate it. Therefore, the conclusion was that the orange picked on 19 December had the most Vitamin C. The reason he thinks is because Vitamin C is a water soluble vitamin and oranges picked on January 6 and 12 were so much bigger with more juices.

There are many factors that can affect the vitamins factors of an orange. For example, pre and post harvesting factors like the type and amount of fertilizers given in the plantations, the duration before the orange is tested for the vitamins and one of the most important factors: temperature. In this Literature review we will be focused on the affect heat on Vitamin C.

Vitamin C is a sensitive molecule that is altered in the presence of heat. In research study of: Temperature Effects on Vitamin C Content in Citrus Fruits it has been found that the degradation of Vitamin C starts from the moment the fruit is plucked from the tree. Places with low temperature during the night produces citrus fruits with higher vitamin C levels whereas, places that are hot and tropical produces fruits with lower levels of vitamin C. Increase in temperature generally reduces the concentration of vitamin C. It is also evidence from pH values of Orange of 3.6 compared to Lime, Lemon and Grape of 2.35, 2.45 and 3.01 respectively in this research.

So in conclusion, among citrus fruits Oranges have the highest Vitamin C rates especially due to the temperature of the environment they grow in.Steven Nagy had done research on how much Vitamin C is lost during oxidation and about Vitamin C content in citrus fruits, concluding that oranges are one of the most potent in Vitamin C, and that about half of vitamin C is lost when exposed to harsh weather/atmospheric conditions.

1.2 Research Questions

What is the rate at which Vitamin C decreases in citrus fruits in a natural environment?

What causes the degradation of Vitamin C in oranges?

1.3 Hypothesis

If the oranges are stored in temperatures of about 1 - 5 degrees Celsius, the amount of Vitamin C retained in the oranges will be more compared to oranges that are stored in other places with higher temperatures.